The present invention relates generally to optical fiber-based spatial light modulation systems such as are utilized in real-time display systems, laser and fiber optic communications systems, commercial lighting systems, laser surgery, and other applications. The present invention relates more particularly to a fiber optic spatial light modulation system in which the optical power launched into individual fibers of an optical fiber bundle is digitally controlled to thereby enable precise control of the total optical power transmitted by the bundle to a remote site and/or precise control of the optical intensity pattern transmitted by the bundle to the remote site.
Real-time display systems based on spatial light modulators (SLMs) have been developed. An exemplary real-time display system for large screen projection televisions uses a digital micromirror device (DMD) as a spatial light modulator between a light source and a display optics system that includes a projection lens. DMDs manufactured by Texas Instruments and Hughes Aircraft (Raytheon) are commercially available. A DMD includes a static random access memory (SRAM) and an array of micromirrors suspended above the SRAM. There is a one-to-one correspondence between the memory cells of the SRAM and the micromirrors. Each micromirror and its corresponding memory cell comprise an individually addressable pixel element. Each micromirror can be tilted to either plus or minus 10 degrees (i.e., .+-.10.degree.) about a torsion axis depending upon the binary value (either "1" or "0") of the data bit stored in the corresponding memory cell. Each micromirror either reflects or does not reflect incoming light from the light source (i.e., it is either "on" or "off") into the projection optics, depending upon its tilt angle. The micromirrors that are tilted to the on position reflect the incoming light through the projection lens and onto a screen, and the micromirrors that are tilted to the off position reflect the incoming light away from the projection lens to be trapped, to thereby produce a desired spatial image on the screen.
Shades of gray can be achieved by appropriately modulating the proportion of time is during each video frame that each micromirror is in the on position, e.g., a micromirror which is in the on position for zero time during a video frame produces black for the corresponding pixel on the display screen, and a micromirror which is in the off position for 100% of the time during a video frame produces white for the corresponding pixel on the display screen. Color may be added by either using a color wheel or by using a triad of DMDs for each pixel element. Illustrative DMDs and display systems incorporating the same are disclosed in U.S. Pat. Nos. 5,517,347 and 5,442,411 which are both assigned to Texas Instruments and which are both incorporated herein by reference.
In conventional fiber optic light distribution or modulation systems, a plurality of light sources are provided for a corresponding plurality of respective optical fiber bundles (cables) which feed light to different sections of the system. Spatial light modulation is achieved by independently modulating the intensity of the light sources. Thus, the intensity of the light launched into all of the optical fibers of each fiber bundle is identically modulated. In order to provide adequate variegation across the system (i.e., adequate spatial light modulation), the required number of fiber bundles may be relatively large, which, in turn, results in a large number of both light sources and light modulators. The size, cost, complexity, and limited spatial light modulation characteristics of the conventional fiber optic light distribution systems constitute significant drawbacks and shortcomings.
Based on the above and foregoing, it can be appreciated that there presently exists a need in the industry for a fiber optic light modulation system which overcomes the above-described drawbacks and shortcomings of the conventional fiber optic light modulation system. The present invention fulfills this need in the industry.